Blocked engine fuel return line

[Veikra]

I have issues with the dipaco fuel return line kit, hoses crack. I decided to test for restriction of the hard line ontop the engine. Seems it's blocked from both return nipple where the injector's fuel return line.

I can blow in the fuel return line on the left side of engine, the one that goes down to the cooler. The blockage seems to be between that hose and the nipples where the fuel return lines of injectors plug in.

Is that a solenoid just before the hard return line split to the fprv and to the 3/8" nipple going to the fuelcooler/tank ?

video:
https://www.youtube.com/watch?v=dfbox_15La4

 

[Dozerboy]

That valve you posted is for the fuel rail only. There shouldn't be any restriction/valve in the injector fuel return that I'm aware of.

 

[malibu795]

On the block, The 1/8" nipple is return, the 1/2" nipple is supply from the tank, and the test port connects to supply.

The injector return feeds into a 5/16" line and snakes accrose the Y bridge picks up the cp3 return line then goes to the line that is by the glow plug module.. There's 3-4 rubber hose connections along the way as well..

Pop the passenger side off and pressurize the metal tube should blow out what ever restrictions is there

 

[Veikra]

Ok so basically, it's supposed to be freeflowing, even with engine off, as expected.

Funny though, I think that picture at the end of my video is a sensor that is on the return line, not on the supply side. Is it a fuel return temp sensor ?

I will try pressurizing it, but not before I can reach the rubber line of the cp3, else I bet that rubber hose on it will blow off the cp3.

Glad to know I have found something wrong with it cause it's driving me crazy

 

[Veikra]

That valve you posted is for the fuel rail only. There shouldn't be any restriction/valve in the injector fuel return that I'm aware of.

Are you talking about the fuel pressure relief valve ? Cause that's not what im refering to. It looks like a sensor on the return line near the fuel pressure relief valve. I poster a picture at the end of the video.

My bet is a temperature sensor

 

[malibu795]

Ok so basically, it's supposed to be freeflowing, even with engine off, as expected.

Funny though, I think that picture at the end of my video is a sensor that is on the return line, not on the supply side. Is it a fuel return temp sensor ?

I will try pressurizing it, but not before I can reach the rubber line of the cp3, else I bet that rubber hose on it will blow off the cp3.

Glad to know I have found something wrong with it cause it's driving me crazy

Yes that's fuel return sensor.. And yes supposed to be free flowing..

15psi shouldn't blow it off.. This lines are a PITA to get to though

 

[Dozerboy]

Are you talking about the fuel pressure relief valve ? Cause that's not what im refering to. It looks like a sensor on the return line near the fuel pressure relief valve. I poster a picture at the end of the video.

My bet is a temperature sensor

Ya I was never mind

 

[Chevy1925]

On the block, The 1/8" nipple is return, the 1/2" nipple is supply from the tank, and the test port connects to supply.

The injector return feeds into a 5/16" line and snakes accrose the Y bridge picks up the cp3 return line then goes to the line that is by the glow plug module.. There's 3-4 rubber hose connections along the way as well..

Pop the passenger side off and pressurize the metal tube should blow out what ever restrictions is there

Make sure you disconnect or plug off the return line for the injectors on the driver side. You don't want what ever crap is in there trying to be forced back to them

 

[Veikra]

Alright, I removed the fuel return temperature sender and both injector tubes and blew everything. so it's free of restrictions on the engine..

but whatever it was went to the tank and blocked there, takes 10 psi to push fuel through . Im dropping the tank as soon as I can.

I made sure the line is all fine and the fuel cooler as well, so it's in or on top of the tank now.

Pretty easy pie.

Also, I believe pressure can stay in the tank, but not vaccuum when the fuel gets low right ? Just making sure

 

[malibu795]

Was fuel cap off or loose when you blew the line? They usually lift about 10psi if they are tight .. they work just like a radiator cap

 

[Veikra]

There was a lot of restriction even with the cap off. I dropped the tank and cleaned everything up, and enlarged the fuel return hole (the 1mm hole in the trash can thingy that clips underneat) Kinda silly that the 3/8 ID hose necks down to 1/16 of an inch, but there must be a reason *shrugs*

I found a bit of flaky orangeblack flakes at the bottom of the trash can, and a aluminium seal from an additive can. Dunno if that one was causing issues.